News Release

New book by NIU anthropologistsheds light on mystery monkey

DeKalb, Ill. — Few people have ever seen one in person, so here’s a description: They’re silky black and a tad bigger than a squirrel, with slender claw-like fingers, very long tails and bouffant-like manes. They prefer to dine on grasshoppers but will settle for fungi.

“They’re very cute,” says Leila Porter, a biological anthropologist at Northern Illinois University. She is arguably the world expert on the rare callimico monkeys that scurry and leap through the understory of the Bolivian rainforest, which is also home to jaguars, pumas and a wide assortment of snakes.

Porter is one of the few people worldwide who have ever observed callimicos in the wild for an extended period. Her pioneering fieldwork resulted in the first detailed information on the ecology and behavior of the endangered species, known scientifically as Callimico goeldii. And her new book, “The Behavioral Ecology of Callimicos and Tamarins in Northwestern Bolivia” (Prentice Hall), offers students a scholarly and relevant study of these elusive and unusual primates.

Working with guides and assistants, Porter has spent a decade doing research in remote areas of the Amazon basin of northern Bolivia, where she has tracked the monkeys for months at a time.

Unlike their close relatives, the tamarins, lion tamarins and marmosets who view humans with curiosity, shy callimicos avoid contact with people.

“They usually run and hide before they can be seen,” Porter says. “That’s probably why they had never before been the focus of a long-term research project. It took us about seven months to get a group of them used to being followed by us. Eventually, we could get within a few feet of them.”

The callimicos are particularly interesting from an evolutionary standpoint, which is why they’re of interest to anthropologists. Tamarins and marmosets almost always give birth to twins, which are raised communally. Communal care is highly unusual among mammals, including primates. But the group child-rearing strategy would seem to make evolutionary sense because of the difficulty of rearing more than one offspring.

Callimicos have single offspring, yet they also use the same communal child-rearing strategy.

“It appears that callimicos twinned at one time during their evolutionary past, but they went back to having single babies,” Porter says. “I hope to learn whether there are ecological reasons why callimicos have reduced their litter sizes.”

The Field Museum and Chicago Zoological Society, which manages Brookfield Zoo, have provided grant funding for Porter’s work, which began with her doctoral thesis. The zoo has special interest in callimicos, and its scientists have occasionally worked alongside Porter during her tracking expeditions.

Ten callimicos arrived at Brookfield Zoo in 1977, after officials at O’Hare International Airport confiscated the animals from an animal seller. Keepers raised the animals behind the scenes, learning as they went. Today the zoo has a colony of callimicos and is in charge of captive management of callimicos in zoos across the United States.

Understanding how the South American monkeys thrive in the wild is important to conservation efforts. In addition to parental care, Porter’s new book delves into the diet, social behavior and habitat of the callimicos, using tamarins for comparison.

Study of the callimicos’ diet yielded one of the more unusual findings. While the monkeys prefer to eat fruit and insects, they consume large quantities of fungi during the dry season when food is scarce.

“That’s not a normal primate diet,” Porter says. “We’re now doing more detailed work to find out how their diet of fungi affects the monkeys’ ranging pattern and social life. Fungi are distributed in the forest differently than plants and insects. And whereas tamarins have small territories, callimicos are more nomadic. They’ll use an area for awhile, and then they seem to pack their bags and move on. We want to figure out why.”

Porter learned just last week that she is being awarded a grant from the National Geographic Society that will fund her research for 2007. Her Bolivian field team is working to habituate a new group of callimicos. She will join the team next summer for further study and hopes to bring students to Bolivia the following year.